Engines associated with work machines such as earthmoving and excavating equipment as well as over the road and off-road vehicles not only provide motive force for the particular work machine or other vehicle but such engines also power peripheral devices such as hydraulic pumps, cooling fans, compressors, air conditioners, generators (alternators) and other parasitic load components. Depending upon the particular work machine or other vehicle, the engine may be operated at a substantially constant speed or at variable speeds where instantaneous changes in output power are needed. In a similar fashion, some parasitic loads may require a substantially constant power input such as a cooling fan operating at a particular fan speed regardless of engine speed, whereas other parasitic loads may require a variable power input under certain operating conditions, even at the same engine speed, such as a hydraulic pump providing power to various hydraulic components during a digging or trenching operation.
Control systems for controlling the operation of an engine are also known and are commonly used on work machines and other vehicles. By sensing various operating parameters such as engine speed, throttle/fuel injection position, manifold pressure, various temperatures and other engine operating parameters, appropriate output signals can be made to various systems so as to operate the engine more efficiently and optimally depending upon the particular work task being performed. Since an engine controller typically monitors the power generated by the engine and the amount of power being required by various operating components of the work machine or other vehicle, and since this information is typically broadcasted or outputted by the engine controller for use by other systems in optimally controlling a particular work task being performed, it is important that the engine controller accurately broadcast the net power output of the engine including taking into account the power necessary to operate parasitic loads. Since the engine controller does not typically know the nature and level of the parasitic loads being imposed upon the engine during a particular work task, the net power output of the engine broadcasted by the engine controller is deficient; it does not compensate for all parasitic load operation; and it does not yield an accurate determination of the amount of power that the engine must generate at any particular point in time. This inaccuracy is exaggerated with respect to work machines such as large earthmoving and excavating equipment, track type tractors and a wide variety of other types of heavy duty equipment wherein large amounts of power are required to drive certain types of parasitic loads.
Accurately determining the net power output of a particular engine is likewise complicated due to the fact that many manufacturers purchase the basic engine separate and apart from the various parasitic load components which will be added later to the completed work machine or other vehicle. Once the engine, vehicle chassis and all related accessories and components are assembled, the engine is mated with a particular vehicle chassis and all of the accessory drives and other parasitic load components including the transmission and associated drive train are linked and coupled thereto. Since the engine manufacturers do not know what type of parasitic loads will be associated with a particular engine and, as a result, do not know the particular power requirements associated with such parasitic loads, they cannot program the associated engine controller to compensate for the wide variety of different power requirements associated with the operation of a wide variety of different parasitic loads when determining the net power output of the engine. This mating of the engine with the vehicle chassis and its associated parasitic load components exemplifies the difficulty in accurately compensating for the power requirements associated with any parasitic load encountered during a particular work task.
It is therefore desirable to provide a method and apparatus for more accurately determining the net power output of an engine available for performing a particular work task taking into account and compensating for all parasitic loads encountered during completion of such task. It is also desirable to provide a method and apparatus that will provide real time information indicative of available engine power to ensure that the available net power output of the engine is adequate to accomplish a particular task such as control operation of the engine and/or peripheral devices associated therewith.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.